fix more typos

Author: gfldex

doc/Type/Signature.pod6

@@ -619,9 +619,9 @@ the parameter to produce a C<List>.  Each element of that list will be bound
 directly as raw parameter.
 
 X<|trait,is readonly>
-To explicitly as for a read-only parameter use the C<is readonly> trait.
+To explicitly ask for a read-only parameter use the C<is readonly> trait.
 Please note that this applies only to the container. The object inside can very
-well have mutator functions and Perl 6 will not enforce immutability on the
+well have mutator methods and Perl 6 will not enforce immutability on the
 attributes of the object.
 
 Traits can be followed by the where clause: